JPS61282597A - Foaming method and device for method of construction of shield excavation - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Technical Field) The present invention aims to reduce the excavation resistance of the face against the rotary cutter in the shield type tunnel excavation method, and to provide fluidity and water-tightness against the pickpocket. The present invention relates to a method and apparatus for generating air bubbles that are supplied to a pressure chamber or face.

(Prior art) In the shield type tunnel excavation method, by injecting air bubbles into the pressure chamber or face in front of the bulkhead of the shield body,
It is possible to reduce the excavation resistance of the rotary cutter in the ground face, and to provide a fluidizing cup and water-stopping properties to the slide in the pressure chamber. A foamer whose cylindrical body is filled with particles such as glass beads is used as a device for generating air bubbles to be supplied to the front of the partition wall of the shield body, and a foaming agent is supplied to the foamer. The mixture of solution and pressurized air is foamed by passing through the foamer and supplied to the pressure chamber or face in front of the partition wall.

By the way, the appropriate amount of bubbles to be supplied depends on the amount of excavation by the shield excavator, that is, the excavation speed of the shield excavator.For example, when the excavation speed increases, the amount of bubbles supplied to the foamer is increased accordingly. It is necessary to increase the supply of agent solution.

When increasing the amount of blowing agent solution supplied to the foamer, the pressure is also increased to provide a commensurate amount of pressurized air; Pressure losses within the tank also increase. For this,
Requires extremely high pressure pressurized air to compensate for the pressure loss,
Furthermore, in order to generate this pressurized air, a high-pressure and therefore large-sized near compressor is required as a pressurized air supply source. Furthermore, when the excavation speed of the shield excavator decreases, it is necessary to supply low-pressure pressurized air accordingly, but there is a problem in that delicate pressure control is difficult with a large near compressor.

Furthermore, in reality, it is not easy to carry a large air P compressor into the limited space of the shield body, and operating it not only significantly narrows the working space inside the shield body, but also This forces a decline in work efficiency.

(Objective of the Invention) Therefore, the object of the present invention is to provide a system that can accommodate the speed of the shield tunneling machine without increasing the size of the pressurized air supply source required to generate the bubbles used in the shield tunneling method. It is an object of the present invention to provide a foaming method for shield excavation method and its device, which enables supply of an appropriate amount of foam.

(Structure and Effects of the Invention) The present invention is characterized in that the bubbles supplied to the front of the partition wall of the shield body are generated by stirring a foaming agent solution and pressurized air.

According to this foaming method, bubbles are generated by stirring energy given to the foaming agent solution and pressurized air, so the maximum number of bubbles obtained is approximately equal to the amount of foaming agent solution and pressurized air supplied. increase or decrease proportionately. Therefore, it is possible to use a device of a scale capable of supplying the minimum amount of pressurized air necessary for generating bubbles, the supply amount of which is increased or decreased depending on the speed of the shield tunneling machine.

Further, the foaming device according to the present invention includes a conduit connected to a supply source of a foaming agent solution, a conduit connected to a supply source of pressurized air, and a bubble guide pipe that guides bubbles in front of a partition wall of a shield main body. The foaming agent solution and pressurized air are supplied to the stirring device and the stirring device is operated to easily generate bubbles.

Further, in the foaming device according to the present invention, a flow rate control valve is provided in the bubble guide pipe. It is characterized by

The flow control valve allows the pressure difference between the inlet and outlet of the stirring device to be reduced by substantially reducing the diameter of the bubble guide tube, thereby reducing the blowing agent solution in the stirring device. By extending the residence time of pressurized air, more stirring energy can be applied to both. As a result, smaller diameter bubbles can be obtained. = (Example) The features of the present invention will become clearer from the following description of the illustrated embodiment.

FIG. 1 shows an example of a foaming device 10 for carrying out the foaming method according to the present invention.

The foaming device 10 includes a conduit 14 connected to a source 12 of a foaming agent solution, a conduit 18 connected to a source 16 of pressurized air, and air bubbles in front of a bulkhead 20 of a shield body (not shown). It includes a stirring device 24 provided between the bubble guide tube 22 and the bubble guide tube 22 that guides the bubbles.

In the illustrated example, the bubble guide tube 22 opens into a pressure chamber 26 formed between the partition wall 20 and a rotary cutter (not shown) rotatably supported on the shield body.

Instead of or in addition to the above-mentioned example, the bubble guide pipe may be installed, for example, so as to open toward the face through the center of the rotary cutter.

The supply source 12 of the foaming agent solution consists of a tank 12a containing the foaming agent solution, and a variable flow rate pump 12b provided in the conduit 14 for introducing the foaming agent solution in the tank into the conduit 14. . The conduit 14 is provided with a flow meter 28 for measuring the flow rate of the foaming agent solution flowing inside the conduit toward the stirring device 24 by the operation of the variable flow rate pump 12b. The foaming agent solution includes water, CMCTE-(+
(manufactured by Chill Night) and Hozolith #505 (manufactured by Hozolith Bussan ■) at a ratio of 1001.1.2 and 0.41, respectively, and a solution can be used.

On the other hand, a near compressor can be used as the pressurized air supply source 16. The near compressor is 3~10Kg
/cm2 and has the ability to supply air. By operating the near compressor, pressurized air at a predetermined pressure is supplied to the stirring device 24 via the conduit 18. The conduit 18 is provided with a pressurized air flow rate regulating valve 3o, a flow meter 32, and a pressure gauge 34 in order from the pressurized air supply source 16 toward the stirring device 24.

The ratio between the amount of foaming agent solution and the amount of pressurized air is set in advance to a predetermined value depending on the soil quality of the ground to be excavated.

The foaming agent solution conduit 14 is connected to a stirring device @24 and a pressure gauge 3.
4 and is connected to the pressurized air conduit 18.

Therefore, the foaming agent solution and pressurized air can be supplied to the stirring device 24 in a gas-liquid mixed state. Instead of this example,
Both conduits 14.18 can also be connected independently to the stirring device 24; in the example shown, a pressure gauge 34 can be arranged between the connection point of both conduits 14.18 and the stirring device 24. I can do it. The pressure measured in this case is that of a gas-liquid mixture of foaming agent solution and pressurized air.

The bubble guide tube 22 is provided with a flow rate regulating valve 36 and a pressure gauge 38 in order from the stirring device 24 toward the partition wall 20 .

The agitation device 24 includes a casing (not shown) provided with an inlet for receiving fluid and an outlet for the agitated fluid, one end connected to a motor 40 disposed outside the casing, and the casing. A so-called pipeline mixer comprises a stirring shaft (not shown) extending along its axis and having stirring blades fixed therein, or a casing provided with a fluid inlet and an outlet, and a casing arranged within the casing. The pump is composed of a centrifugal pump (not shown) such as a well-known centrifugal pump or a turbine pump, which is equipped with a rotationally driven impeller.

The foaming agent solution and pressurized air introduced into the casing through the conduit 18 connected to the inlet of the casing of the pipeline mixer are agitated by the rotation of the stirring blades, thereby creating a large number of bubbles. It is formed. The bubbles are conveyed through the guide tube 22 toward the partition wall 2° by the pressurized air that is continuously supplied later, and are supplied to the pressure chamber 26. The amount of bubbles supplied increases or decreases in proportion to the amount of foaming agent solution and pressurized air supplied, and the rotation speed of the stirring blade increases in proportion to the amount of foaming agent solution and pressurized air supplied.
It is desirable to set the difference between the pressure on the outlet side and the pressure on the inlet side of step 4 to be small, thereby reducing the flow rate of the foaming agent solution and pressurized air from the inlet side to the outlet side. The residence time within the stirring device 24 can be made longer. As a result, more stirring energy can be applied to the foaming agent solution and pressurized air. In this way, bubbles can be efficiently generated and the bubbles can be made finer like shaving cream.

The pressure on the outlet side of the stirring device 24 can be increased by reducing the opening degree of the flow rate regulating valve 36.
(2) Preferably, it is 2.

In the illustrated example, the constantly changing indicated values of both pressure gauges 34 and 38 are detected by means of detection means (not shown).
Conductive wires 42 and 44 respectively connected to both pressure gauges via
is electrically transmitted to the pressure control device 46 by. Pressure control device! 1
46 detects the difference between the two indicated values and operates a valve operating means (not shown) attached to the flow rate regulating valve 36 and electrically connected to the pressure control device 46 via a conductive wire 48 to adjust the indicated value. A command signal is sent to the valve operating means to adjust the opening degree of the flow rate regulating valve 36 so that the difference becomes equal to the set value.

Furthermore, in order to increase or decrease the amount of bubbles to be supplied in accordance with changes in the excavation speed of the shield tunneling machine, the amount of the foaming agent solution and the amount of pressurized air supplied are increased or decreased by appropriate means. The number of revolutions of the motor 40, that is, the number of revolutions of the stirring blade, is also adjusted in accordance with increases and decreases in the supply amount of the foaming agent solution and the supply amount of pressurized air. To adjust this rotational speed, a rotational speed control device 50, such as an inverter, is electrically connected to the motor 40 via a conductor 52. It is electrically connected to the foaming agent solution flow meter 28 and the pressurized air flow meter 32 through the flowmeter, respectively, and the flow rates sent from both flow meters are summed. Based on this, the rotation speed control device 50 controls the motor 40 to maintain the rotation speed proportional to the added flow rate.

When the stirring device 24 is configured with the centrifugal pump, it is desirable to make the differential pressure between the outlet side and the inlet side of the stirring device 24 smaller than in the case of the pipeline mixer. The fluid feeding effect of the impeller is reduced, and the fluid within the casing is agitated by the impeller. In this example, since the stirring device itself has a feeding action, a large number of bubbles generated by being stirred by the impeller are moved through the guide tube 22 mainly under the feeding action.

By the way, there are cases where the entire amount of the foaming agent solution supplied to the stirring device 24 remains without being used for generating bubbles.For such cases, as shown in FIG.
A similar stirring device 58 can be connected in series to the stirring device 24 via piping 60 . As a result, the foaming agent solution remaining without forming bubbles in the stirring device 24 is removed from the stirring device 5.
This can be formed into bubbles by stirring at step 8. Further, the bubbles formed in the stirring device 24 are stirred when passing through the stirring device 58, thereby forming fine bubbles with a smaller diameter. The motor 62 which is the power source of the stirring device 58 is also connected to a conductor 64 as in the example shown in FIG.
It is connected to the rotation speed control device 50 via. In addition,
If desired, further or more stirring devices (not shown) can be connected in series to the stirring device 58. Also.

Multiple stirring devices can be connected in parallel, and this ~
A larger amount of bubbles can be obtained at once.

[Brief explanation of the drawing]

FIG. 1 relates to the present invention. A block diagram schematically showing a foaming device for implementing the foaming method, FIG. 2, is a block diagram similar to FIG. 1 showing another example of the present invention. 10.58: Foaming device, 12: Source of foaming agent solution, 14,18: Conduit, 16
: Pressurized air supply source, 20: Partition wall of shield body, 22: Air bubble guide tube, 24:
Stirring device, 36: Flow rate control valve. Agent Patent Attorney Nobuyuki Matsunaga Figure 1 t Figure 2

Claims (5)

[Claims] (1) A foaming method for the shield excavation method, which generates air bubbles to be supplied to the front of the partition wall of the shield body by stirring a foaming agent solution and pressurized air. (2) A stirring device installed between the conduit connected to the supply source of the foaming agent solution, the conduit connected to the supply source of pressurized air, and the bubble guide tube that guides the bubbles to the front of the partition wall of the shield body. Foaming equipment for the shield excavation method, including: (3) A stirring device provided between the conduit connected to the supply source of the foaming agent solution, the conduit connected to the supply source of pressurized air, and the bubble guide tube that guides the bubbles in front of the partition wall of the shield body. and a flow rate control valve provided in the bubble guide pipe, a foaming device for a shield excavation method. (4) the stirring device comprises a pipeline mixer;
A foaming device according to claim (3). (5) The foaming device according to claim (3), wherein the stirring device comprises a centrifugal pump.